Wrist pin sensing system and method

Abstract

A method, and a system employing the method, for determining a position of a rotational part in a reciprocating machine. The system includes a quadrature encoder and an interrupter coupled to the rotational element. As the interrupter rotates with the wrist pin, the quadrature encoder generates some binary signals based on the rotation of the wrist pin. A digital-to-analog converter then converts the binary signals into a single analog signal. The system then wirelessly transmits the single analog signal for processing by other remote components.

1. A reciprocating machine comprising:
 a crank case; 
 a crankshaft supported for rotation within the crank case; 
 a cylinder defining a bore; 
 a piston reciprocable within the bore of the cylinder, the piston having at least one bearing surface; 
 a wrist pin supported by the at least one bearing surface; 
 a connecting rod having a first end pivotally connected to the crankshaft and a second end pivotally connected to the wrist pin to convert reciprocal movement of the piston into rotation movement of the crankshaft; 
 a rotational element having alternating slits and solid portions and being rotationally coupled to the wrist pin; 
 a first binary signal generator including a first optical signal generator on one side of the rotational element and a first optical signal receiver on an opposite side of the rotational element and aligned with the first optical signal generator, such that the first binary signal generator generates a first binary signal in response to respective slits and solids of the rotational element being positioned between the first optical signal generator and the first optical signal receiver, the first binary signal generator being decoupled from rotational movement with the wrist pin; 
 a second binary signal generator including a second optical signal generator on the one side of the rotational element and a second optical signal receiver on the opposite side of the rotational element and aligned with the second optical signal generator, such that the second binary signal generator generates a second binary signal in response to respective slits and solids of the rotational element being positioned between the second optical signal generator and the second optical signal receiver, the second binary signal generator being decoupled from rotational movement with the wrist pin; and 
 a circuit configured to receive the first and second binary signals and convert the first and second binary signals into a single analog signal, wherein the first and second binary signals provide a first digit and a second digit in a two-digit binary signal that is converted to the single analog signal. 
 
     
     
       2. The machine of  claim 1 , wherein the circuit comprises a transmitter wirelessly transmitting the single analog signal. 
     
     
       3. The machine of  claim 1 , wherein further comprising a processor receiving the transmitted signal and processing the received signal. 
     
     
       4. The machine of  claim 1 , wherein the circuit comprises a digital-to-analog converter converting the two-digit binary signal into the single analog signal. 
     
     
       5. The machine of  claim 1 , wherein each of the first and second optical signal receivers has a receiving width, wherein each of the slits has a slit width, and wherein the slit width is greater than the receiving width. 
     
     
       6. The machine of  claim 1 , wherein the circuit comprises a resistor ladder network. 
     
     
       7. The machine of  claim 1 , wherein the rotational element comprises a castle nut. 
     
     
       8. A method for determining a position of a rotational element having alternating slits and solids, the method comprising:
 generating a first optical signal at a first position on one side of the rotational element; 
 receiving at least a portion of the first optical signal at a first position on an opposite side of the rotational element in response to the respective slits and solids of the rotational element; 
 generating a first binary signal in response to the received first signal; 
 generating a second optical signal at a second position on the one side of the rotational element; 
 receiving at least a portion of the second optical signal at a second position on the opposite side of the rotational element in response to the respective slits and solids of the rotational element; 
 generating a second binary signal in response to the received second signal; and 
 converting the first and second binary signals into a single analog signal, wherein the first and second binary signals provide a first digit and a second digit in a two-digit binary signal that is converted to the single analog signal. 
 
     
     
       9. The method of  claim 8 , further comprising wirelessly transmitting the single analog signal. 
     
     
       10. The method of  claim 9 , further comprising wirelessly receiving the transmitted signal remotely. 
     
     
       11. The method of  claim 8 , wherein receiving at least a portion of the second optical signal comprises receiving the at least a portion of the second optical signal within a receiving width, wherein each of the slits has a slit width, and wherein the slit width is greater than the receiving width. 
     
     
       12. The method of  claim 8 , wherein converting the first and second binary signals comprises converting the first and second binary signals into the single analog signal using a resistor ladder network. 
     
     
       13. The method of  claim 8 , wherein the rotational element comprises a castle nut. 
     
     
       14. A method for sensing a position of a wrist pin rotationally coupled to a rotational element having a plurality of apertures, the method comprising:
 emitting first and second signals from one side of the rotational element; 
 receiving at least a portion of the respective first and second signals through the apertures on an opposite side of the rotational element; 
 generating respective first and second binary signals in response to the received first and second signals; and 
 generating a single analog signal in response to the respective first and second binary signals, wherein the first and second binary signals provide a first digit and a second digit in a two-digit binary signal that is converted to the single analog signal. 
 
     
     
       15. The method of  claim 14 , further comprising wirelessly transmitting the single analog signal. 
     
     
       16. The method of  claim 15 , further comprising wirelessly receiving the transmitted signal remotely. 
     
     
       17. The method of  claim 14 , wherein receiving at least a portion of the respective first and second signals comprises receiving at least a portion of the respective first and second signals within a receiving width, wherein each of the apertures has an aperture width, and wherein the aperture width is greater than the receiving width. 
     
     
       18. The method of  claim 14 , wherein generating a single analog signal comprises converting the first and second binary signals into the single analog signal using a resistor ladder network. 
     
     
       19. The method of  claim 14 , wherein the rotational element comprises a castle nut.